1. Technical Field
The present invention relates to an image inspection result determination apparatus, an image inspection system, and an image inspection result determination method, and more particularly to determination of failure of position matching for an image comparison inspection.
2. Background Art
Conventional inspections of printed products such as printed papers are conducted by visual inspection, but inspection apparatuses have been introduced to conduct the inspection as a post-processing operation of an offset printing. As to the inspection apparatus, the printed products are visually inspected by an operator to select a printed product having satisfactory image quality, and then the selected printed product is scanned to generate a master image, which is to be used as a reference image for the inspection. A portion of the master image and a corresponding portion of inspection target image (i.e., printed product) are compared with each other by scanning the inspection target image. Based on difference between the master image and the inspection target image, defect of the inspection target image can be determined.
Printing apparatuses of digital type, not using a press plate, such as image forming apparatuses using electrophotography typically print images with a small volume, and also print different images for each page (i.e., variable printing), in which generation of a master image from a printed product as a reference image is not efficient. In this type of image forming apparatuses, the master image can be generated from print data to efficiently conduct the inspection for the variable printing.
Further, to enhance precision this comparison inspection, a pattern recognized in a scanned image and a pattern recognized in a master image can be used to conduct a position matching of these two images.
However, even if the position matching is conducted, the position matching may not be conducted correctly. For example, when the same image pattern is repeatedly drawn, the above position matching method may conduct false position matching. If a comparison inspection is conducted under a condition of false position matching, each pixel is compared under a condition that the master image and the scanned image are deviated, in which the scanned image is determined as defect.